Two-speed alternating-current elevator control



July 28, 1925. 1,547,739

E. M. BOUTON ET AL TWO-SPEED ALTERNATING CURRENT ELEVATOR CONTROL FiledOct. 11, 192.2

WVENTOR Edgar M. Eou'ton and gay P. r 'iigbee.

ATTORNEY Patented July 28, 19

UNITED STATES PATENT OFFICE.

EDGAR u. no

UTON, OF EAST PITTSBURGH, AND RAY Y. HIGIBEE, OF WILKINSBUBG,

I PENNSYLVANIA, ASSIGNORS T0 WESTINGHOUSE ELECTRIC AND MANUFACTUR- INGCOMP NY, A CORPORATION OF PENNSYLVANIA.

TWO-SPEED ALrnnNArme-oun'nENT ELEVATOR CONTROL.

To all whom it mag concern:

Be it known that we, EDGAR M. BoU'roN, a citizenof the United States,and a resident of East Pittsburgh, in the county of Allegheny and Stateof Pennsylvania, and RAY: P. Hiennna citizen of the United States, and aresident of Wilkinsburg, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Two-SpeedAlternating-Current Elevator Controls, of which the following is aspecification.

Our invention relates to motor-control systems and it has particularrelation to such systems of control as areemployed in connection withelevators, machine tools and similar machines.

The object of our invention is to provide means for controlling thespeed and torque of an alternating-current motor of the two speed type,commonly employed in elevator service and having separate low andhighspeed windings.

Sui invention is more particularly applicable to the control of atwo-speed motor of the well-known squirrehcage type.

in the operation 0:? ternating-current meters or" the type hereindescribed, it is common practice to start the motor by connecting itslow-speed winding to the source of power and, thereafter, transferdirectly to the high-spear winding, with without resistor in circu t andfinally exfrom circuit. En such systems, sone djiiculty has been "n. lsmooth acceleraour system. control, we propose tc start the mot by:iLIlS of its lo -speed nally connect only in circus. When oth highlow-speed windings -e in circnit simultaneous obtained which, certaininstances, is rather close to the minimum speed. With a motor having athree-to-one speed range, the intermediate speed is only about 25 percent greater than the minimum speed. By weakening the low-speed winding,a second an intermediate speed is Application filed October 11, 1922..Srial No. 593,665.

and higher intermediate speed is obtained from which the transition tofull speed is less abrupt. I

Our invention will be described in connection with the accompanyingdrawing, in which Figure 1 is a diagrammatic representation of a.two-speed, three-phase alternating-current squirrel-cage motor employedin connection with our invention,

Fig. 2 is a diagrammatic representation of circuits and apparatusembodying our invention,

Fig. 3 is a diagrammatic representation of the control circuits employedin the operation of the system shown in Fig. 2, and

Figs. 4 and 5 represent, diagrammatically, certain of the mainconnections employed in our system.

A two-speed alternating-current motor 1 is provided with low-speedprimary windings 2 and high-speed primary windings 3. These windings areso arranged that they may be connected externally to resistors. Resistorsections 4 are connected in circuit with the motor windings and may beexcluded, when so desired, by elcctro-magnetic switches 5. Resistorsections 6 may be con- Switches 8 co circuits for excluding thelow-speed windin s 2 and switches 10 are connected ror excluding thehighspeed motor windi gs 3 from circuit. An clectro-ma netioaliyoperable switch 11 is controlled ny means of knife-switches 12.

is apparent that, in addition to the line switch 11, reversing switchesmay be employed in the customary manner but these have been omitted.since they constitute no part of our invention. "We provide a manuallyoperable switch 18, as illustrated in Fig. 3 for transferring the motorfrom low to liiglrspeed connections. A relay 14C, having an operatingcoil 15, is also controlled by means of the switch 18. An interlock 16is mechanically connected to switch 7. Switch 10 is provided with anormally open interlock 17 and a normally closed interlock' 18. v A finori'nally closed interlock -19 isattached to switch -8. Power is suppliedfrom a suitable source, for the operation of our system, through lineconductors 20,21 and 22.

Assuming the apparatus to be in its inoperative or illustratedpositions, andalso asconductors 20, 21 and 22, when relay suming that nopower has been supplied to wer 1s sup-, plied to the lineconductors,sw1tch ,(Fig. 3) immediately closes, since its operating coilis connected, through interlock 19 and '14, to conductors 21 and 22.Switch Q 5 is thereafter closed when its operating coil is connectedtoconductors'21 and 22 through interlock 17 of switch 10.

To start the motor, switches 12 are next closed to connect the operatingcoil of lines switch 11' to conductors 21;and 22 (Fig. 2.).

Since switches 5 'and 10 are closed, it is evident that the motor isstarted with lowspeed windings 2 only in circuit. The motor is v furtheraccelerated by closing switch 13 (Fig. 3) thereby energizing theoperating coil 150i relay 14. The opening of relay 14. fl'ects theopening of switch 10 to insert the high' speed windings 3 in seriesrelation with the low-speed windings 2,

The motor then'accelerates to a speed corresponding to the. excitationproduced by the serles connections of its low and high-speed windings.Switch 7 is closed by means ofthe interlock of the switch 10, whichcompletes a circuit for the operating coil of switch-7,

extending through switch 13 to line conductors 20 and 21. The opening ofswitch 10 affects the opening of swltch 5 through the interlock 17,thereby insertlng resistor sections 4 in series relation with motorwind-- in 2 and 3. (Fig. 4). 0 he closure of switches 7 insertsresistors i 6 in shunt relation to the windings The I magnetizationofprimarywindings 21s thus 5 reduced in accordance fwith the efiectlvevalves of resistors 4 and 6 to further accelerate the motor. (Fig. 5.) Fnally, switches 8 close to exclude the lo'w-speed circuits and toenergize only the high-speed windings 3. The motor now operates at itsmaximum speed. s

To efi'ect slow-down, switch 13 is o ened, thereby opening switches 7and 8 an closing switches 10. switches 5 are already open and resistors4 and low-speed windings 2 are now in circuit, while high-speed windings3 are short- It will be .noted that intermediate speed connections inwhich the motor windings are, arranged first inseries relation and then,as illustrated in Fig. 5,

the low-speed windings 2 are shunted by means of the illustratedresistors.- These.

connections have been found necessary only during the acceleratingperiod. IDeceleration is satisfactorily accomplished by the insertion ofresistors in series relation with the I low-speed windings when thehigh-speed windings are excluded from circuit. -In some instances, itmay be desirable to substitute reactors of suitable'value in lace of theseries resistors 4 or in place of t e shunt resistors- 6. The efiect ofresistance and reactance in motoncircuits is well understood and willrequire no further explanation.

Also, for deceleration particularly, it may.

be advisable to connect resistors 1n shunt relation to the high-speedwindings instead of entirely excludingthe windings prior to operation onthe low-speed windings.

We claim as our invention:

1. The method of accelerating an alternating-current motor having lowand highspeed windings which consists in connecting the low-speedwindings incircuit, connecting the low and high-speed windings in seriesrelation, weakening the efl'ect of said low speed windings andfinally'excluding said low-speed windings from circuit.

2. The method of accelerating an induction motor havin low andhigh-speed primary windings w ich consists in connecting the low-speedwindings in circuit, connecting the low and high-speed windingsin seriesrelation, weakening the efiectof said lowspeed windings and finallyexcluding said low-speed windings from circuit.

3. The combination with an alternating current motor having a high and alow- 1 speed winding and controlling means therefor, of a'plurality ofresistors, means for connecting said windings and some'of the resistorsin series relation and means forconnecting others of said resistors inparallel relation to one of said windings.

4. The combination with an alternating current motor having low andhigh-speed primary windings and controlling means therefor, of aplurality of resistors, means for connecting said windings and some ofthe resistors in series relation and means for connecting others of saidresistors in parallel relation to said low-speed winding.

5. The combination with an alternatin current motor having a low and abig speed winding, of means forconnecting said windings in seriesrelation and means for weakening the magnetization of one ofisaidwindings while so connected.

6. The combination with an alternatingcurrent motor having a low and ahigh-speed winding connected in series relation, of means for energizingonly the low-speed winding, means for energizingsaid windingssimultaneously and means for gradually shunting said low-speed winding.

7. The combination with an alternatingcurrent motor having low andhigh-speed primary windings, a plurality of speed-controlling resistorsassociated therewith, and electro-responsive means for selectivelyrendering the speed windings effective or ineffective and for connectingsaid resistors 10 in shunt relation to certain of said windings duringacceleration and deceleration of the motor.

In testimony whereof, we have hereunto subscribed our names this 7th dayof October, 15

EDGAR M. BOUTON. RAY P. HIGBEE.

